Levees provide protection from flooding in communities, including industrial, commercial, residential, and agricultural communities. However, should a levee break, extreme damage to the surrounding communities can occur. Levee failures can result from erosion, slides within the levee embankment or the foundation soil, or from animals burrowing into the levee. For example, when beavers dug into a levee in the California Delta, crops and farm communities were flooded with water. Damages and cleanup costs were estimated at $90 million dollars.
Farming on the lands also scrapes away layers of soil, gradually pushing the land below sea level in a process called subsidence. As the land falls below sea level, additional pressure is placed on the levees to control flooding of the lands. Continual subsidence occurs due to ongoing soil placement on the levees in order for the levee elevation to be maintained. This additional soil placement causes increased loading of the toe of the existing levees inducing potential failure of the levee.
Should multiple levees collapse from tidal fluctuations or seismic events, farms, homes and crops would be flooded, and rail lines, gas pipelines and aqueducts could be damaged. Water quality may even be significantly compromised and the ecosystem of neighboring plants and animals may be endangered.
To maintain levees, the current practice on the water side is to buttress the slope with soil and rock, called riprap, to protect the levee against buffeting by wind-whipped waves and the force of winter high tidal conditions. However, the rocks and soil add weight to the levee, which causes the levee to subside. This repeated addition of rocks or soil every few years exacerbates subsidence and increases maintenance costs to governmental agencies.
Alternative measures used to reinforce levees are Fiberglass Reinforced Polymer (FRP) sheet piling. However, the FRP must be put into levees using vibratory hammers, or dynamically driven using a removable mandrill. Unfortunately, most levees are built in flood prone areas or of basic compressible soil that was laid down in a stratified manner. The introduction of water pressure through the layered soil reduces the levee strength making it susceptible to failure from strong vibrations. Furthermore, homes built next to the levees may become damaged due to the vibrations because they too were constructed over vibrationally sensitive soil.
Levees may also be reinforced with steel, concrete, or cement barriers. These types of installations would require the use of vibrational or hydraulic driving equipment. In general, large heavy equipment must be used to install these types of barrier systems. In many cases, the levees are unable to support the additional equipment loads and accessibility on the levees is typically limited. All of which serves to increase the expense of installing barriers in levees. Furthermore, these barriers may be prone to corrosion with the exception of concrete. All of these barriers are labor intensive during installation. In addition, these barrier systems require heaving installation equipment, limiting the accessibility on the levee.